Learn about the different types of skin

Several criteria are used to classify the different types of skin¹. For example, Fitzpatrick's classification, first described in 1975, is based on skin color and its response to sun exposure. It is used to determine the proper type of sun protection factor or to predict the risk of skin cancer, among others^1,2. However, from a cosmetic point of view, skin is classified according to several factors related to its balance: sebaceous secretion, hydration and sensitivity level³. Thus, each type of skin will have its own characteristics and require different cares. The type of skin is determined by genetics, although it will also be affected by other factors and can change with time³.

Based on these characteristics, there are five types of healthy skin: normal, dry, oily, combination (both oily and dry skin) and sensitive^3,4. Below, we describe the main characteristics of each type of skin.

Normal Skin

This skin is neither too dry nor too oily. It has regular texture, no imperfections and a clean, soft appearance, and does not need special care^3,4.

Sensitive Skin

Sensitive skin is more prone to react to stimuli to which normal skin has no reaction⁵. It is a fragile skin, usually accompanied by feelings of discomfort, such as heat, tightness, redness or itching^4-6. This type of skin loses its barrier (or protective) function, making it easy for microorganisms and irritant substances to enter it, and increasing the possibility of having an infection and allergic reactions^5,6. It is a delicate skin that needs more care to fight dryness, roughness and its usual appearance⁵. Sometimes, it is referred to as irritated skin instead of sensitive, but these terms are synonymous and there are no dermatological differences between them⁶.

Dry Skin

In many cases, dry skin is caused by external factors such as the weather, low air humidity and immersion in hot water, and it is usually temporary⁷. However, for some people it may occur more often and even be a lifelong condition.7 Since dry skin can crack leaving it more exposed to bacteria, although in general this is not serious, it may cause other skin disorders, such as eczema, or be more prone to infections if not properly managed⁷.

Dry skin signs and symptoms may vary depending on different factors such as age, health status or their cause⁷. It is generally characterized by a feeling of tightness and roughness. It may also acquire an ashy gray color, with occurrence of desquamation, itching, redness and small cracks⁷. Cracked skin is usually observed in very dry skin and presents small cracks, which, in more serious cases, may be deeper and even bleed⁷.

Atopic skin is a skin disease characterized by dry skin that leads to desquamation and irritation and causes upsetting symptoms, such as itching⁸. The main cause is genetic predisposition, although other factors may trigger its occurrence or aggravate the condition as well, which may be environmental, allergic, related with food and even with some clothes⁸.

Oily Skin

Oily skin has a porous, humid and bright appearance³. It is caused by excessive fat production by sebaceous glands, and usually determined by genetic and/or hormonal causes^3,9. It is frequent in adolescents and young people under 30 years old³, and usually related with the occurrence of acne⁹.

Combination Skin

Based on its location, it presents characteristics of both dry and oily skin since the distribution of sebaceous and sweat glands is not homogeneous. The area with more oil is usually the T- zone (forehead, nose, and chin), while the skin on the cheeks is normal or dry^3,4.

In general, it is important to pay attention to skin appearance because, regardless of the type of skin you have, there are certain characteristics that could be a sign of a skin problem.

Scaly Skin

Repeated skin irritation due to environmental factors, such as the sun, the wind, dryness or excessive humidity, may cause skin desquamation, that is the detachment of big scales from the epidermis, which sometimes look like fine dust. However, desquamation may also be the result of some condition, such as an allergic reaction, a fungal or staphylococcus infection, an immune system disorder or cancer, and of oncological treatments. In these cases, desquamation is usually accompanied by itching¹⁰.

Red Spots

There is a large number of dermatological causes and diseases for the appearance of red spots or rash, including infections, heat, allergens, immune system disorders and medications¹¹.

Skin Moles

Moles are dark dots or spots on the skin that usually appear during childhood and adolescence. They are caused by groups of pigmented cells. In general they are harmless, but it is best to check them with a dermatologist if they change size, shape or color, or if itching or bleeding occurs, since some may become cancerous¹².

References

1. Roberts, W.E. Skin Type Classification Systems Old and New. Vol. 27, Dermatologic Clinics. Dermatol Clin; 2009 Oct. p. 529–33.

2. Gupta, V., Sharma, V.K. Skin typing: Fitzpatrick grading and others. Clin Dermatol. 2019 Sep;37(5):430–6.

3. American Association for the Advancement of Science (AAAS). Determine Your SkinType. Science NetLinks [Internet]. [Cited 2020 Mar 10]. Available at: http://sciencenetlinks.com/student-teacher-sheets/determine-your-skin-type/

4. Mayo Clinic. Moisturizers: Options for softer skin [Internet]. 2019 Oct 18. Available at: https://www.mayoclinic.org/diseases-conditions/dry-skin/in-depth/moisturizers/art-20044232

5. Berardesca, E., Farage, M., Maibach, H. Sensitive skin: An overview. Vol. 35, International Journal of Cosmetic Science. Int J Cosmet Sci; 2012. p. 2–8.

6. Richters, R., Falcone, D., Uzunbajakava, N., Verkruysse, W., Van Erp, P., Van De Kerkhof, P. What is sensitive skin? A systematic literature review of objective measurements. Vol. 28, Skin Pharmacology and Physiology. S. Karger AG; 2014. p. 75–83.

7. Mayo Clinic. Dry Skin [Internet]. 2019 Aug 20 [cited 2020 Feb 19]. Available at: https://www.mayoclinic.org/diseases-conditions/dry-skin/symptoms-causes/syc-20353885

8. Mayo Clinic. Atopic dermatitis (eczema) [Internet]. 2018 Mar 06. Available at: https://www.mayoclinic.org/diseases-conditions/atopic-dermatitis-eczema/symptoms- causes/syc-20353273

9. MedlinePlus. Oily Skin [Internet]. [Cited 2020 Feb 19]. Available at: https://medlineplus.gov/ency/article/002043.htm

10. Mayo Clinic. Peeling skin [Internet]. 2018 Apr 06 [cited 2020 Feb 19]. Available at: https://www.mayoclinic.org/symptoms/peeling-skin/basics/causes/sym-20050672

11. Mayo Clinic. Slide show: Common skin rashes [Internet]. 2019 Sep 28 Available at: https://www.mayoclinic.org/skin-rash/sls-20077087?s=1

12. Mayo Clinic. Moles [Internet]. 2019 Nov 19 [cited 2020 Feb 19]. Available at: https://www.mayoclinic.org/diseases-conditions/moles/symptoms-causes/syc-20375200